School of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama, 226-8501, Japan.
Graduate School of Science, Chiba University, 1-33 Yayoicho, Chiba, 263-8522, Japan.
Sci Rep. 2019 Mar 19;9(1):4868. doi: 10.1038/s41598-019-41057-9.
Transcription and DNA damage repair act in a coordinated manner. Recent studies have shown that double-strand DNA breaks (DSBs) are repaired in a transcription-coupled manner. Active transcription results in a faster recruitment of DSB repair factors and expedites DNA repair. On the other hand, transcription is repressed by DNA damage through multiple mechanisms. We previously reported that TLP, a TATA box-binding protein (TBP) family member that functions as a transcriptional regulator, is also involved in DNA damage-induced apoptosis. However, the mechanism by which TLP affects DNA damage response was largely unknown. Here we show that TLP-mediated global transcriptional repression after DSBs is crucial for apoptosis induction by DNA-damaging agents such as etoposide and doxorubicin. Compared to control cells, TLP-knockdown cells were resistant to etoposide-induced apoptosis and exhibited an elevated level of global transcription after etoposide exposure. DSBs were efficiently removed in transcriptionally hyperactive TLP-knockdown cells. However, forced transcriptional shutdown using transcriptional inhibitors α-amanitin and 5,6-dichloro-1-ß-D-ribofuranosylbenzimidazole (DRB) slowed down DSB repair and resensitized TLP-knockdown cells to etoposide. Taken together, these results indicate that TLP is a critical determinant as to how cells respond to DSBs and triggers apoptosis to cells that have sustained DNA damage.
转录和 DNA 损伤修复以协调的方式进行。最近的研究表明，双链 DNA 断裂 (DSBs) 以转录偶联的方式进行修复。活跃的转录导致 DSB 修复因子更快地募集，并加速 DNA 修复。另一方面，转录通过多种机制被 DNA 损伤抑制。我们之前报道过，TLP 是 TATA 盒结合蛋白 (TBP) 家族成员，作为转录调节剂，也参与 DNA 损伤诱导的细胞凋亡。然而，TLP 影响 DNA 损伤反应的机制在很大程度上尚不清楚。在这里，我们表明 TLP 在 DSB 后介导的全局转录抑制对于 DNA 损伤剂（如依托泊苷和阿霉素）诱导的细胞凋亡至关重要。与对照细胞相比，TLP 敲低细胞对依托泊苷诱导的凋亡具有抗性，并在依托泊苷暴露后表现出更高水平的全局转录。在转录活性高的 TLP 敲低细胞中，DSBs 被有效地去除。然而，使用转录抑制剂 α-鹅膏蕈碱和 5,6-二氯-1-β-D-核糖呋喃基苯并咪唑 (DRB) 强制转录关闭会减缓 DSB 修复，并使 TLP 敲低细胞对依托泊苷重新敏感。总之，这些结果表明 TLP 是细胞对 DSBs 做出反应并触发持续 DNA 损伤细胞凋亡的关键决定因素。
